1. Field of the Invention
The present invention relates to an article of manufacture, in the form of a novel gel pharmaceutical formulation adapted for local anesthesia. More particularly, the present invention relates to a gel pharmaceutical formulation for local anesthesia which has excellent percutaneous absorption, provides local anesthesia easily merely by applying the formulation to the skin, enables elimination of various kinds of pain, such as the pain at the time of injection, can be removed easily from the skin, and causes no soiling of fingers, hands or cloths.
2. Description of the Related Art
Heretofore, in simple situations, such as saturation of a wound, and for injection with a relatively large syringe, subcutaneous injection of a local anesthetic is conducted as a preliminary treatment. Also in some hospitals, a cream or a gel ointment containing a local anesthetic is used as ODT (Occlusive Dressing Technique) when a surgical operation is necessary in a wide range.
However, the pain at the time of penetration of the injection needle cannot be avoided by the subcutaneous injection technique. Creams and ointments for local anesthesia have drawbacks in that pharmaceuticals cannot be applied quantitatively and their removal after the application without causing soiling of hands, fingers and cloths is not easy.
As the local anesthetic, xylidine compounds such as lidocaine, bupibacaine, mepibacaine, and the like, and aminobenzoic acid compounds, such as procaine, tetracaine, and the like, are known. These compounds in base form or as the salt of hydrochloric acid are widely used for the surface anesthesia in dental areas, for local anesthesia, verteba anesthesia, epidural anesthesia, and the like.
By making use of the local anesthetic effect of a local anesthetic, an externally attached pharmaceutical formulation containing lidocaine has been proposed for curing, for example, neuralgia in herpes zoster and neuralgia after herpes zoster (Japanese Patent Application Laid Open No. Heisei 4(1992)-305523). However, the externally attached pharmaceutical formulation has a drawback in that a long time (about 4 to 8 hours) is required for exhibiting the local anesthetic effect after the pharmaceutical formulation is attached to the skin because the lidocaine content is as low as 1 to 10% by weight.